1. Field of the Invention
This invention relates to a method for manufacturing a golf ball.
2. Description of the Related Art
When a golf ball is manufactured by injection molding or compression molding, flash is formed on a parting line of the cover material, and it is necessary to remove the flash.
This flash has been conventionally removed by buffing the parting line of the cover material. To be specific, as described in Japanese Patent Provisional Publication No. 60-232861 and Japanese Patent Provisional Publication No. 63-174801, a golf ball is held between vertically arranged holding devices, the golf ball is rotated, an equatorial position (a parting line) of the golf ball is contacted by a grindstone or a cutting tool, and flash is removed from the golf ball. In the conventional method, the golf ball and the grindstone are respectively rotated at high speeds. For example, the grindstone is rotated at an extremely high speed of at least 10,000 mm/s.
Hard ionomer resin having bending rigidity of 2800 Kg/cm.sup.2 to 4000 Kg/cm.sup.2 has been conventionally used as cover material of golf balls, however, golf balls recently produced tend to be soft, and cover material for such balls also tends to be soft accordingly.
When a grinding apparatus (which is provided with the foregoing grindstone that rotates at a high speed) for hard cover material is used to buff the soft cover material, a face buffed by the apparatus becomes rough and buffing depths vary owing to differences in ball positioning and ball diameter, and it is not possible to beautifully finish a ball surface.
Moreover, the cover material is soft thermoplastics resin; therefore, ball shavings melt due to friction heat in buffing and stick to the ball surface.
It is therefore an object of the present invention to provide a method for manufacturing a golf ball in which a golf ball, buffed (ground) approximately uniformly in depth with an excellent external appearance, is manufactured.